X32 psABI status

[H. Peter Anvin]

On 02/13/2011 01:10 PM, H.J. Lu wrote:
>>>
>>> 1. Kernel interface with syscall is close to be finalized.
>>

I don't think calling it "finalized" is accurate... it is more
accurately described as "prototyped".

>> Really? I haven't seen this being posted for review yet ;-)
>>
>> The basic concept looks entirely reasonable to me, but I'm
>> curious what drove the decision to start out with the x86_64
>> system calls instead of the generic ones.
>>
>> Since tile was merged, we now have support for compat syscalls
>> in the generic syscall ABI. I would have assumed that it
>> was possible to just use those if you decide to do a new
>> ABI in the first place.
>> 
>> The other option that would have appeared natural to me is
>> to just use the existing 32 bit compat ABI with the few
>> necessary changes done based on the personality.

The actual idea is to use the i386 compat ABI for memory layout, but
with a 64-bit register convention.  That means that system calls that
don't make references to memory structures can simply use the 64-bit
system calls, otherwise we're planning to reuse the i386 compat system
calls, but invoke them via the syscall instruction (which requires a new
system call table) and to pass 64-bit arguments in single registers.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.